In many industrial applications, such as the manufacture of foods and beverages, hard surfaces commonly become contaminated with soils such as carbohydrate, proteinaceous, and hardness soils, food oil soils, fat soils, and other soils. Such soils can arise from the manufacture of both liquid and solid foodstuffs. Carbohydrate soils, such as cellulosics, monosaccharides, disaccharides, oligosaccharides, starches, gums, and other complex materials, when dried, can form tough, hard to remove soils, particularly when combined with other soil components such as proteins, fats, oils, minerals, and others. The removal of such carbohydrate soils can be a significant problem. Similarly, other materials such as proteins, fats, and oils can also form hard to remove soil and residues.
Food and beverage soils are particularly tenacious when they are heated during processing. Foods and beverages are heated for a variety of reasons during processing. For example, in dairy plants, dairy products are heated on a pasteurizer (e.g., HTST—high temperature short-time—pasteurizer or UHT—ultra-high temperature—pasteurizer) in order to pasteurize the dairy product. In brewing, wort is boiled to breakdown the components of the grain into fermentable sugars. Also, many food and beverage products are concentrated or created as a result of evaporation.
Specific examples of food and beverage products that are concentrated using evaporators include dairy products such as whole and skimmed milk, condensed milk, whey and whey derivatives, buttermilk, proteins, lactose solutions, and lactic acid; protein solutions such as soya whey, nutrient yeast and fodder yeast, and whole egg; fruit juices such as orange and other citrus juices, apple juice and other pomaceous juices, red berry juice, coconut milk, and tropical fruit juices; vegetable juices such as tomato juice, beetroot juice, carrot juice, and grass juice; starch products such as glucose, dextrose, fructose, isomerose, maltose, starch syrup, and dextrine; sugars such as liquid sugar, white refined sugar, sweetwater, and inulin; extracts such as coffee and tea extracts, hop extract, malt extract, yeast extract, pectin, and meat and bone extracts; hydrolyzates such as whey hydrolyzate, soup seasonings, milk hydrolyzate, and protein hydrolyzate; beer such as de-alcoholized beer and wort; and baby food, egg whites, bean oils, and fermented liquors.
Clean-in-place (CIP) cleaning techniques are a specific cleaning regimen adapted for removing soils from the internal components of tanks, lines, pumps, and other process equipment used for processing typically liquid product streams such as beverages, milk, juices, etc. CIP cleaning involves passing cleaning solutions through the system without dismantling any system components. The minimum CIP technique involves passing the cleaning solution through the equipment and then resuming normal processing. Any product contaminated by cleaner residue can be discarded. Often CIP methods involve a first rinse, the application of the cleaning solutions, and a second rinse with potable water followed by resumed operations. The process can also include any other contacting step in which a rinse, acidic or basic functional fluid, solvent or other cleaning component such as hot water, cold water, etc. can be contacted with the equipment at any step during the process. Often the final potable water rinse is skipped in order to prevent contamination of the equipment with bacteria following the cleaning and/or sanitizing step.
Conventional CIP techniques however are not always sufficient at removing all types of soils. Specifically, it has been found that low density organic soils, e.g., ketchup, barbeque sauce, are not easily removed using traditional CIP cleaning techniques. Thermally degraded soils are also particularly difficult to remove using conventional CIP techniques.
Brewery soils are another type of soil that is particularly difficult to remove from a surface. Brewing beer and wine requires the fermentation of sugars derived from starch-based material e.g., malted barley or fruit juice, e.g., grapes. Fermentation uses yeast to turn the sugars in wort or juice to alcohol and carbon dioxide. During fermentation, the wort becomes beer and the juice becomes wine. Once the boiled wort is cooled and placed in a fermenter, yeast and/or bacteria is propagated in the wort and it is left to ferment, which requires a week to months depending on the type of yeast or bacteria and style of the beer or wine. In addition to producing alcohol, fine particulate matter suspended in the wort settles during fermentation. Once fermentation is complete, the yeast also settles, leaving the beer or wine clear, but the fermentation tanks soiled with dead yeast cells, proteins, hop resins, and/or grape skins.
Fermentation is sometimes carried out in two stages, primary and secondary. Once most of the alcohol has been produced during primary fermentation, the beer is transferred to a new vessel and allowed a period of secondary fermentation. Secondary fermentation is used when the beer requires long storage before packaging or greater clarity.
Often during the fermentation process in commercial brewing, the fermentation tanks develop a ring of soil, i.e., brandhefe ring, which is particularly difficult to remove. Brandhefe rings are tough, tacky material composed of dried-up yeast, albumen, and hop resins. Traditional CIP methods of cleaning fermentation tanks do not always remove this soil. Thus, brewers often resort to climbing inside of the tanks and manually scrubbing them to remove the soil.
Furthermore, traditional CIP cleaning is performed in one of two ways with a caustic cleaning composition typically composed of sodium hydroxide or with an acid-based cleaning composition. Both traditional methods of CIP cleaning suffer from a number of setbacks. Acidic systems provide inferior cleaning and often are unable to adequately remove the aforementioned soils. This results in the need to expend greater time, energy, and effort to adequately clean the food processing surface. Alkaline cleaning systems are generally more effective at removing the soils; however, they suffer from problems of their own. Traditional caustic soda-based cleaning cannot be performed under high CO2 conditions due to the risk of tank implosion caused by the removal of CO2 by reaction with sodium hydroxide. Various types of food processing surfaces are often under an enriched CO2 atmosphere. For example, in brewery applications this may be the result of intentionally creating the enriched CO2 atmosphere to exclude oxygen from the vessel during fermentation or as a by-product of fermentation. When caustic soda is used under an enriched CO2 atmosphere, it reacts with the CO2, which results in substantial reduction in pressure. The change in pressure is so substantial that the tank will implode. Thus, in order to clean under alkaline conditions with caustic soda, the food processing surface must be vented to remove the CO2. Adequate venting can take extensive amounts of time. This increases the amount of time that the food processing surface is soiled and not in condition to be used for its intended purpose, which is not time or cost effective.
Moreover, traditional caustic cleaning methods necessitate fairly high temperatures for optimal cleaning. Typical cleaning must be performed at temperatures of at least about 60-75° C. Therefore, the existing cleaning methods require the additional time and energy to sufficiently heat the food processing surface or washing vessel.
Thus, there is a significant need for an alkaline cleaning system capable of cleaning under an enriched CO2 atmosphere. Moreover, there is a need for an improved method for removing food and beverage soils that are not easily removed using conventional cleaning techniques. Furthermore, there is a need for an improved method for removing food and beverage soils at lower temperatures than existing methods. It is against this background that the present invention has been made.
Accordingly, it is an objective of the claimed invention to develop a highly effective alkaline cleaning system for food processing surfaces.
It is a further object of the claimed invention to provide an alkaline cleaning system that can be used under an enriched CO2 atmosphere.
It is a further object of the claimed invention to provide a cleaning system that overcomes the problems in the art that prevent cleaning with caustic formulas or require extensive time—often four to twelve hours—to vent the CO2 from a food processing surface.
A further object of the invention is to develop a system that allows for lower temperature cleaning, which decreases the energy and time necessary to heat up the food processing surface.